Should anyone ask, Apple has an interesting ZFS upgrade path (or not?)

Interestingly, Apple is going to need to be able to upgrade from HFS+ filesystems to ZFS.  Matthew alerted me to United States Patent Application 0070112891 filed by  Apple in the last month.  I expect this could equally be applied to an HFS+ upgrade to ZFS path.

SUMMARY OF THE INVENTION: In accordance with one aspect of the invention, a first file-system can be converted to a second file-system while one or more files stored on the computer readable medium remain virtually undisturbed in the same location. It will be appreciated that the second file-system can be generated primarily based on the location of the file(s) already stored on the computer readable medium. Thus, the file(s) can remain “in place” without being modified or rewritten. It will also be appreciated that there is no need for rewriting or storing the file(s) while the file-system is being converted. In one embodiment, a FAT file-system (e.g., FAT32) is converted to an HFS file-system (e.g., HFS Plus) by generating HFS data structures (Catalog, Allocation File and Extents) for file(s) already stored in the FAT file-system. The HFS data structures that are used to effectively implement a HFS file-system are primarily generated based on the number and location of the file(s). The number and location of the file(s) can be determined primarily based on the FAT file-system’s data structures (FAT and Directory). It should be noted that the file-system conversion process can be stopped before the FAT file-system indicators (partition map and boot sector which identify the operating-system) are overwritten. After the HFS data structure have been generated and successfully verified for the file(s) already stored on the computer readable medium, the HFS file-system can effectively replace the FAT file-system by modifying the partition map and writing a volume header that may overwrite that boot sector). It will also be appreciated that a HFS file-system can be converted to a FAT file-system in accordance with one embodiment of the invention. In general, any file-system used to organize and store files can be converted using the invention as the invention utilizes the information about the organization of files provided by a first file-system to generate a second file-system.

I wonder if another embodiment is ZFS?  Thanks Matthew.

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